A computer security tool called nmap was used on the public network you use (Cable, DSL, FiOS, etc.). While scanning ports, and sending prob strings to open ports, your public IP had an open port from Internet to your Printer. What you are seeing on the printout is a string attempting to prop SQLi port, but instead, ALL DATA RECEIVED ON PORT FORWARDED DIRECTLY TO PRINTER OUTPUT. That is, anything sent to that port of your public IP address gets printed.
Ask yourself: Do I have printing available from my iPhone or Android device? Did I install special software when I got my printer to do "printing from the web" on my computer? Did I enable printing from iCloud?
These are signes that your printer is just hanging off the public internet and anyone can send junk to your printer and it will print!